The motivation to create AmpliCell
About 5% of all
mobile phone users suffer from moderate to severe hearing loss.
Only a quarter of all people reporting hearing impairment own and use a hearing aid,
but most hearing impaired are nowadays users of mobile phones.
940 millions mobile phones and 6-7 million hearing aids have been sold 2007.
Opposed to hearing aids, the market penetration for mobile phones is 81% in the US as of 2007.
Many European countries have more mobile phone subscriptions than people and the worldwide
subscriber count has reached the equivalent of half the population.
Sources:
Adding the usual GSM signal artifacts and environmental noise, these people have difficulties to follow phone conversations.
Often, they follow a simple but not necessarily satisfying strategy: they increase the volume of their mobile phones to the maximum.
This results in a frequency independent linear amplification which does not reflect the user’s
individual amplification needs.
How Traditional Hearing Aids address Individual Amplification Needs
The characteristics of hearing losses are highly individual and hearing thresholds
vary substantially from person to person. The most common type of hearing loss is the
sensorineural hearing loss which is caused by an impaired inner ear. This type of hearing
loss is characterized by the loudness recruitment phenomenon. To compensate loudness
recruitment more amplification is needed for soft sounds than for loud sounds.
The core functionality of the software hearing aid is thus (a) compensating for the
frequency dependent sensitivity loss of the impaired human ear and (b) compensating
for loudness recruitment by means of a non-linear automatic gain control (AGC).
AmpliCell addresses this issue and helps out by implementing a software hearing aid on the iPhone.
The implementation of the software hearing aid is based on the core functionalities of traditional hearing aids,
but it benefits from the
technological possibilities of modern mobile phones.
People with a mild to moderate hearing loss that will benefit most from a better sound quality AmpliCell provides.
Technological Possibilities for Amplification in Mobile Phones
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In comparison to traditional (physical) hearing aids, the frequency range is much wider,
ranging in many cases from 20 Hz to 20.000 Hz. While the smaller frequency range of traditional
hearing aids is sufficient for speech, this wider range allows excellent sound quality when listening to music.
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Since the input to the signal processing in the software hearing aid is either a GSM signal or
multimedia content, the signal from the phone’s microphone itself is not amplified. This simple
fact could be very beneficial for the development of the software hearing aid.
Firstly, feedback as known from physical hearing aids cannot occur. Also, a signal delay in the
order of magnitude of one hundred milliseconds will go unnoticed by the user.
Thus, a look-ahead delay can be introduced in the AGC algorithm in order to improve sound quality.
Also, there is no risk for
comb filter effects due to the
superposition of direct (un-amplified) and delayed path, no unpleasant pre-echo effects can
occur and no stuttering is provoked by any delayed and amplified own voice signal.
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A software hearing aid in a mobile phone can make a qualified guess whether the signal to be amplified
is speech or music: a signal that stems from the phone’s GSM unit consist most likely of speech
while the content of media, such as MP3 files, consists most likely of music.
This assumption allows tailoring the signal processing to either speech intelligibility or sound quality.
About AmpliCell
AmpliCell is a small start-up company that is about to be founded in Barcelona, Spain.
Its two founders are:
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Joachim Neumann
Dr. Joachim Neumann is a German physicist living in Barcelona.
He earned his Ph.D. degree at one of the leading audiological
laboratories in Europe: the department for medical physics at the
University of Oldenburg, Germany.
Since 1997, Dr. Neumann is working in the hearing aid industry.
He obtained his profound knowledge in digital signal processing
at the research center 'Eriksholm' which does "blue sky" research
for the Danish hearing aid manufacturer Oticon, one of the largest
hearing aid manufacturers. His developments found their way into
millions of hearing aids and he owns several patents in the field.
joachim@joachimneumann.com
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Nicolas Wack
Nicolas Wack is a telecommunication engineer who received in 2003 his degree with majors in
signal processing and computer science from the ENST in Paris.
Since then, he has been leading the development of the music analysis and the search engine
developed at the Music Technology Group of the Universitat Pompeu Fabra, which is also now
commercialized by BMAT.
wackou@gmail.com
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